Question

13+14+15+16+17+18+19+20+21

Answer 1

153 nha bạn

Answer 2

(13+17)+(14+16)+(19+21)+15+18+20=30+30+40+33+20= 60+40+20+33=100+20+33=120+33=153

Answer 3

(13+17)+(14+16)+15+18+19+20+21=20+20+20+15+18+21+19=30+33+49=115

Answer 4

13 + 14 + 15 + 16 + 17 + 18 + 19 + 20 +21

= ( 13 + 21 ) + ( 14 + 20 ) + ( 15 + 19 ) + ( 16 + 18 ) + 17

= 34 + 34 + 34 + 34 + 17

= 34 x 4 + 17

= 136 + 17

= 153

Answer 5

13+14+15+16+17+18+19+20+21

Dãy trên có :(21-13):1+1=9(số)

tổng 13+14+15+16+17+18+19=20+21 là:

(13+21)*9:2=153

Answer 6

13+14+15+16+17+18+19+20+21

Dãy trên có :(21-13):1+1=9(số)

tổng 13+14+15+16+17+18+19=20+21 là:

(13+21)*9:2=153 

Vậy : 13+14+15+16+17+18+19+20+21 = 153

Answer 7

153